Chromosomal aberrations are caused by:
1. Change in the structure of the gene
2. Change in the number of chromosomes
3. Change in the arrangement or position of genes
4. Change in the number or arrangement of genes in the chromosomes

 

Subtopic:  Non - Disjunction & Aneuploidy |
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1:2:1 phenotypic and genotypic ratio is found in:
1. Complementary genes. 
2. Pseudo alleles.
3. Blending inheritance 
4. Multiple alleles. 
Subtopic:  Monohybrid Cross: Further Understanding |
 53%
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Possibilities of the blood groups of the children in a family where the father is heterozygous for blood group A and the mother is heterozygous for blood group B would be:
1. Blood Group A and B
2. Blood Group A, B and O
3. Blood Group AB and O
4. Blood Group A, B, AB and O
Subtopic:  Co-dominance |
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Assertion (A):  Turner's syndrome is generally not found in males.
Reason (R):  The disorder occurs due to monosomy.
 
1.  Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.
Subtopic:  Sex Aneuploidy - Turner & Klinefelter Syndrome |
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Consider a test cross between a homozygous recessive yellow-seeded plant with a plant having an unknown seed. 50% of the offspring in the F1 generation have yellow seeds and 50% have green seeds.
Which of the following statements is/are TRUE about the cross?
1. The unknown seed is homozygous recessive for green.
2. The unknown seed is heterozygous for green.
3. All the offspring in the F2 generation will have green seeds.
4. All the offspring in the Fgeneration will have yellow seeds.

1. Only 1.
2. Only 2
3. Only 1 and 4.
4. Only 2 and 3.
Subtopic:  Monohybrid Cross: Further Understanding |
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In a cross between full green pods (FFGC) and constricted yellow pads (ffgg), the percentage of heterozygous dominant offsprings in Fis:
1. \(25 \%\).
2. \(50 \%\).
3. \(75 \%\).
4. \(100 \%\).
Subtopic:  Dihybrid Cross: General Consideration |
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A single gene is usually seen to exhibit a single phenotypic expression. Pleiotropic genes. however, can impact multiple phenotypic expressions. 
Which of these genetic disorders have multiple phenotypic expressions being impacted by a change in a single gene?
1. Thalassemia 
2. Haemophilia
3. Phenylketonuria 
4. Down's syndrome 
Subtopic:  Polygenic Inheritance & Pleiotropy |
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If dark skin colour is controlled by the dominant gene MNO and its recessive allele is mno, what can be DEFINITELY said about the offspring that are dark-skinned?
1. They all have two copies of the dominant alleles.
2. They have at least one copy of the dominant allele.
3. They all have very high exposure to sunlight.
4. They do not have any exposure to sunlight.
Subtopic:  Polygenic Inheritance & Pleiotropy |
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The following statements were noted by a student of grade 12 after studying about Morgan's dihybrid cross experiments with Drosophila. 
1. Two genes chosen in a dihybrid cross are always located on the same chromosome.
2. Genes on the same chromosome are often linked.
3. Linked genes segregate independently during gamete formation.
4. Linked genes do not always obey the law of independent assortment. 
Which of these statement(s) is/are TRUE?
1. only 1
2. only 1 and 2
3. only 2 and 4
4. all- 1, 2, 3, and 4 
Subtopic:  Understanding Linkage |
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The correct statement with respect to Thalassemia in human is:
1. Alpha-thalassemia is controlled by a single gene. 
2. The gene for alpha-thalassemia is located on chromosome-16.
3. Beta-thalassemia is controlled by two closely linked genes HBA-1 and HBA-2.
4. In beta-thalassemia the production of alpha globin chain is affected. 
Subtopic:  Mendelian Disorders: Thalassemia |
 73%
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